Leeann Tweeden, a Los Angeles-based radio host, said the politician "aggressively" kissed her during a rehearsal of a skit while she was on a USO tour and later posed for a photo with his hands on her breasts while she was sleeping on a plane.

Tweeden took to KABC to post the allegations, including a photo of the groping incident, saying that she felt "belittled" and "humiliated."

The senator apologized in a statement later Thursday, saying that he didn't recall the rehearsal but also acknowledged that the photo "wasn't" funny.

Despite his apologetic statement, however, the outcry has been immediate on Twitter, with many users -- Republicans and Democrats alike -- denouncing the senator in varying degrees of critical language and calling for his resignation.

"Franken should resign because what he did was wrong, unethical and possibly criminal. I'm a democrat but wrong is wrong," one user tweeted, while another posted: "I'm a Democrat but the more I see the photo, @alfranken should resign. There is no excuse for violating a woman."

Another tweeted: "If you call for Moore to drop out or be expelled, then you should also call for Franken to resign or be expelled."